The present invention relates to a liquid ejecting apparatus, such as an ink jet printer, and a liquid ejecting head attached to the same, and relates, in particular, to a liquid ejecting apparatus and a liquid ejecting head which allow liquid to be ejected in the form of a liquid droplet in response to an operation of a pressure generating element and thereby form a dot on a target medium.
A liquid ejecting apparatus is an apparatus which comprises a liquid ejecting head capable of ejecting liquid in the form of a liquid droplet, and in which various kinds of liquids can be ejected from the liquid ejecting head. A typical example of the liquid ejecting apparatus is an image recording apparatus such as an ink jet printer (simply referred to as a printer, hereinafter) which comprises an ink jet type recording head (simply referred to as a recording head, hereinafter) serving as a liquid ejecting head, and thereby ejecting liquid ink in the form of an ink droplet from the recording head onto recording paper serving as a target medium, so that the impacted ink forms a dot and thereby achieves image recording. In recent years, such a liquid ejecting apparatus is used not only as an image recording apparatus but also as various kinds of manufacturing apparatuses such as a display manufacturing apparatus.
The recording head of the above-mentioned printer comprises: a plurality of nozzle arrays each composed of nozzle orifices arranged in line and connected to a pressure chamber; and a pressure generating element for generating a fluctuation in the pressure in the pressure chamber. Then, ink stored in an ink cartridge is introduced into the pressure chamber, and then the pressure generating element is driven, so that the ink in the pressure chamber is ejected in the form of an ink droplet from the nozzle orifice.
The liquid droplet amount (weight or volume; referred to as an ejected liquid droplet amount, hereinafter) of an ink droplet ejected from the nozzle orifice increases or decreases depending on the drive voltage value of a driving signal provided to the pressure generating element. Thus, during the manufacturing of the recording head, an averaged liquid droplet amount is acquired for the ink droplets ejected from all the nozzle orifices, so that the drive voltage value of the driving signal is set up such that this averaged liquid droplet amount should equal to a reference value of the design (referred to as a designed liquid droplet amount, hereinafter).
Then, in order that a user should recognize the timing of change of the ink cartridge when the ink in the ink cartridge decreases, the number of times of ejection of the ink droplet is counted. Then, the counted value is multiplied by the liquid droplet amount (weight or volume) of the ink droplet, so that the consumed amount is calculated. Then, on the basis of the consumed amount, the residual amount of the ink in the ink cartridge is notified to the user (see, for example, Japanese Patent Publication No. 5-48552A). This avoids the necessity that a sensor or the like for detecting the residual amount of the ink in the ink cartridge should be provided separately, and thereby allows a simple configuration to acquire the residual amount of the ink.
The driving signal in which the drive voltage value is set up as described above is used in common with the pressure generating element of each nozzle array. Nevertheless, the ejected liquid droplet amount at the time that the ink droplet is ejected in response to the driving signal tends to vary depending on each nozzle array. That is, the ejected liquid droplet amount can be greater than the designed liquid droplet amount in a specific nozzle array, while smaller in another nozzle array. This variation can be attributed to the dimension precision, the assembly precision, and the like of the components.
Such a variation in each nozzle array relative to the designed liquid droplet amount causes various problems. For example, in the above-mentioned printer, in general, each nozzle array corresponds to ink of a different kind (color). Thus, a variation in the ejected liquid droplet amount of each nozzle array affects the hue (color balance) of the image in the recording paper. That is, the color becomes deeper in a nozzle array having an ejected liquid droplet amount greater than the designed liquid droplet amount, while the color becomes lighter in a nozzle array having a smaller ejected liquid droplet amount. For example, when the nozzle array corresponding to magenta has an ejected liquid droplet amount greater than the designed liquid droplet amount, the recorded image becomes reddish in comparison with the image to be originally acquired.
Further, in the case that the ejected liquid droplet amount varies depending on each nozzle array, when the residua amount of the ink in the ink cartridge is to be calculated, an error can arise between the calculated consumed ink amount and the actual consumed ink amount. When such an error arises, an inaccurate residual ink amount is notified to the user. This causes a discrepancy in the timing of change of the ink cartridge recognized by the user from the preferred replacement timing.